Breast MRI: Looking Beyond High-risk Screening

Three years ago, the American Cancer Society (ACS) updated breast cancer screening guidelines for high-risk and dense-breasted, pre-menopausal women, recommending that this subset of patients undergo breast MRI in addition to annual screening mammograms. Since then, breast MRI has played an integral role in high-risk screening. Use of the modality, however, continues to evolve with practices across the country expanding breast MRI beyond high-risk screening, and the technology playing a key role in surgical and radiation treatment planning and cancer staging.

Indeed, experts predict that breast MRI will carve out a more prominent role over the next decade. “The radiology community is still learning this new technology. In the long term, I believe that MRI will become the most powerful tool we have for evaluating patients with breast disease,” says Gillian Newstead, MD, professor of radiology at the University of Chicago Medical Center. She notes that breast MRI is as important among newly diagnosed breast cancer patients as it as among high-risk women.

All newly diagnosed breast cancer patients at the University of Chicago undergo breast MRI; however, this model has not yet been universally adopted across the country. In fact, there is significant variability among facilities regarding the use of breast MRI for surgical planning and cancer staging. “It takes a long time to change the medical community,” acknowledges Newstead.

This month, Health Imaging & IT visits a pair of sites attempting to broaden the role of breast MRI.

A model in flux

With the support of the ACS and other advocacy organizations, MRI has established a strong screening role among high-risk women. Another model is the use of breast MRI for women diagnosed with breast cancer. “In this population, it’s also very clear that the cancer can be found to be more extensive than previously thought, and cancer in the other breast can be found that wasn’t previously discovered,” explains Mitchell D. Schnall, MD, PhD, professor of research radiology at the Hospital of the University of Pennsylvania in Philadelphia.

In fact, clinical studies confirm this role. MRI detected previously unsuspected lesions in 37 percent of women with newly diagnosed breast cancer in a study published in American Journal of Roentgenology in May 2009. MRI also can detect occult breast cancer in the contralateral breast that was not found by mammography. Breast MRI detected breast cancer in the opposite breast in 30 out of 969 women (3.1 percent), with 18 of the 30 testing positive for invasive cancer, reported Constance D. Lehman, MD, PhD, director of breast imaging at Seattle Cancer Care Alliance, in the March 2007 issue of the New England Journal of Medicine.

The increasing role of breast MRI in the diagnosis and management of breast cancer patients can be attributed to the modality’s ability to depict disease and breast cancer that is not otherwise known, with higher sensitivity than mammography, continues Schnall.

Although MRI may better detect the extent of disease than other modalities, additional clinical data do not necessarily translate into improved treatment or outcomes. That’s because many existing treatments were developed in an era preceding sophisticated breast imaging. “Adding MRI to the mix may not help very much because the treatments have been designed to work without [MRI images],” explains Schnall.

Schnall and his colleagues are working to leverage MRI to improve established treatment paradigms for breast cancer patients. “For example,” he offers, “does everyone with breast cancer that is managed by lumpectomy need radiation therapy? We know that 60 percent of patients will not relapse if they don’t have the radiation therapy. Can we identify those patients? If MRI shows localized disease, the radiologist can better tailor treatment to the patient and minimize over-treatment.

In the right setting and in the right hands, Schnall believes breast MRI can play a larger role in surgical planning in the future. “I think there should be a greater role [for MRI] in limiting over-treatment of patients with limited disease who are getting treated more aggressively than they need to be,” he says.

Cancer staging & surgical planning in practice

Breast MRI is the most accurate tool for evaluation of cancer, primarily because it has higher sensitivity than mammography or ultrasound, says Newstead. “It’s become a very important tool, not only for evaluating how much cancer is in the breast that we know about, but also for looking at the opposite breast,” says Newstead.

The University of Chicago Medical Center refers all newly diagnosed breast cancer patients for breast MRI. In this model, radiologists find cancer in the opposite breast in 3 to 6 percent of patients.

In addition to evaluating the extent of disease, breast MRI also can play an important role in surgical planning; however, surgeons remain somewhat divided about the utility of breast MRI in surgical planning. Although surgeons at the University of Chicago Medical Center will not operate without the information that breast MRI provides, some others do not want the information, notes Newstead. “It’s difficult for surgeons to consider all of the information and accurately remove the lesions because the breast is in different positions [during the MRI scan and surgery].” MRI data are acquired with the patient in the prone position, forcing surgeons to adjust perspective as the patient is on her back during surgery.

Identifying and addressing implementation challenges

Although breast MRI presents no ionizing radiation risk, other issues could limit its role and curb wider use. These include the longer length of the exam compared to other breast imaging modalities and the greater expense. In addition, Newstead notes that MRI has been associated with a greater number of false positive findings than mammography; however, the false positive rate may correlate more strongly with physician experience rather than the modality. “I think that’s largely a reflection of inexperience with the technique more than anything else,” says Newstead. In fact, she believes the radiology community is becoming more adept with breast MRI interpretation.

Eyeing the future

Breast MRI imaging remains a work-in-progress with varying usage patterns across institutions and divided opinions about its role in cancer staging and surgical and treatment planning among radiologists and surgeons. The modality is here to stay and will likely continue to make an impact beyond high-risk screening. Increased experience with the modality will lead to an expanded role and changes in the medical community.